Work by C·I·B core team member Dr. Chris Chimimba 's lab at the Department of Zoology & Entomology at the University of Pretoria is shedding new light on invasions of species of the genus Rattus . Since the first record (using molecular data) for Africa of an invasive species of Rattus from Asia , our investigations on members of the genus in southern Africa are continuing using a multidisciplinary approach that includes morphometrics, cytogenetics, molecular analyses, screening for zoonotic potential, and GIS analysis.

The morphometric results suggest that Rattus species can be distinguished morphologically; this paves the way for devising workable identification keys for use by both scientists and the public. Molecular analyses suggest limited variation in one of the species, indicating a single, recent introduction. Data for another species suggests three separate introductions. Although overall disease prevalence in Rattus seems to be much lower than in endemic rodents, one pathogen with known zoonotic potential that causes severe forms of human endocarditis ( inflammation of the inner layer of the heart) has been recorded in one of the Rattus species. Analysis of geographic distributions challenges conventional wisdom regarding the distribution of members of Rattus in the sub-region. Results suggest that Rattus invasions may be much more extensive than previously thought.